The purpose of the study was to find out what special education teachers know about Asperger’s syndrome. In addition, this study attempted to find out if there any significant differences in special education teachers' knowledge about Asperger Syndrome depending on teachers'(gender, education level, teaching experience, and level of professional development) variables. A total of 171 special education teachers from various segregated and inclusive schools in (Riyadh, Al-Baha, Jeddah, and Al-Dammam) in Saudi Arabia were asked to complete the Knowledge of Asperger- revised Scale - revised (KASP-Revised) to determine their level of knowledge about Asperger Syndrome. An analysis of the collected data, using descriptive statistics and analysis of variance, indicated that special education teachers have relatively moderate level of knowledge about Asperger Syndrome. The results also indicated that; female special education teachers, teachers with Master’s degree or above, teachers with (>10) years of experience, and finally, teachers who had a previous professional development, had higher level of knowledge about Asperger Syndrome in comparison with other special education teachers groups.